rpcsvc: Add rpchdr and proghdr to iobref before submitting to transport

Backport of https://review.gluster.org/16613

Issue:
When fio is run on multiple clients (each client writes to its own files),
and meanwhile the clients does a readdirp, thus the client which did
a readdirp will now recieve the upcalls. In this scenario the client
disconnects with rpc decode failed error.

RCA:
Upcall calls rpcsvc_request_submit to submit the request to socket:
rpcsvc_request_submit currently:
rpcsvc_request_submit () {
   iobuf = iobuf_new
   iov = iobuf->ptr
   fill iobuf to contain xdrised upcall content - proghdr
   rpcsvc_callback_submit (..iov..)
   ...
   if (iobuf)
       iobuf_unref (iobuf)
}

rpcsvc_callback_submit (... iov...) {
   ...
   iobuf = iobuf_new
   iov1 = iobuf->ptr
   fill iobuf to contain xdrised rpc header - rpchdr
   msg.rpchdr = iov1
   msg.proghdr = iov
   ...
   rpc_transport_submit_request (msg)
   ...
   if (iobuf)
       iobuf_unref (iobuf)
}

rpcsvc_callback_submit assumes that once rpc_transport_submit_request()
returns the msg is written on to socket and thus the buffers(rpchdr, proghdr)
can be freed, which is not the case. In especially high workload,
rpc_transport_submit_request() may not be able to write to socket immediately
and hence adds it to its own queue and returns as successful. Thus, we have
use after free, for rpchdr and proghdr. Hence the clients gets garbage rpchdr
and proghdr and thus fails to decode the rpc, resulting in disconnect.

To prevent this, we need to add the rpchdr and proghdr to a iobref and send
it in msg:
   iobref_add (iobref, iobufs)
   msg.iobref = iobref;
The socket layer takes a ref on msg.iobref, if it cannot write to socket and
is adding to the queue. Thus we do not have use after free.

Thank You for discussing, debugging and fixing along:
Prashanth Pai <ppai@redhat.com>
Raghavendra G <rgowdapp@redhat.com>
Rajesh Joseph <rjoseph@redhat.com>
Kotresh HR <khiremat@redhat.com>
Mohammed Rafi KC <rkavunga@redhat.com>
Soumya Koduri <skoduri@redhat.com>

> Reviewed-on: https://review.gluster.org/16613
> Reviewed-by: Prashanth Pai <ppai@redhat.com>
> Smoke: Gluster Build System <jenkins@build.gluster.org>
> Reviewed-by: soumya k <skoduri@redhat.com>
> NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
> CentOS-regression: Gluster Build System <jenkins@build.gluster.org>
> Reviewed-by: Raghavendra G <rgowdapp@redhat.com>

Change-Id: Ifa6bf6f4879141f42b46830a37c1574b21b37275
BUG: 1422363
Signed-off-by: Poornima G <pgurusid@redhat.com>
Reviewed-on: https://review.gluster.org/16623
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
Smoke: Gluster Build System <jenkins@build.gluster.org>
Reviewed-by: Prashanth Pai <ppai@redhat.com>
CentOS-regression: Gluster Build System <jenkins@build.gluster.org>
Reviewed-by: Shyamsundar Ranganathan <srangana@redhat.com>

2 files changed, 33 insertions, 3 deletions

diff --git a/rpc/rpc-lib/src/rpcsvc.c b/rpc/rpc-lib/src/rpcsvc.c
index 52b57205f6d..2be54a382f9 100644
--- a/rpc/rpc-lib/src/rpcsvc.c
+++ b/rpc/rpc-lib/src/rpcsvc.c
@@ -1014,6 +1014,7 @@ int rpcsvc_request_submit (rpcsvc_t *rpc, rpc_transport_t *trans,
         struct iovec            iov         = {0, };
         struct iobuf            *iobuf      = NULL;
         ssize_t                 xdr_size    = 0;
+        struct iobref           *iobref     = NULL;
 
         if (!req)
                 goto out;
@@ -1036,20 +1037,33 @@ int rpcsvc_request_submit (rpcsvc_t *rpc, rpc_transport_t *trans,
         iov.iov_len = ret;
         count = 1;
 
+        iobref = iobref_new ();
+        if (!iobref) {
+                ret = -1;
+                gf_log ("rpcsvc", GF_LOG_WARNING, "Failed to create iobref");
+                goto out;
+        }
+
+        iobref_add (iobref, iobuf);
+
         ret = rpcsvc_callback_submit (rpc, trans, prog, procnum,
-                                      &iov, count);
+                                      &iov, count, iobref);
 
 out:
         if (iobuf)
                 iobuf_unref (iobuf);
 
+        if (iobref)
+                iobref_unref (iobref);
+
         return ret;
 }
 
 int
 rpcsvc_callback_submit (rpcsvc_t *rpc, rpc_transport_t *trans,
                         rpcsvc_cbk_program_t *prog, int procnum,
-                        struct iovec *proghdr, int proghdrcount)
+                        struct iovec *proghdr, int proghdrcount,
+                        struct iobref *iobref)
 {
         struct iobuf          *request_iob = NULL;
         struct iovec           rpchdr      = {0,};
@@ -1057,6 +1071,7 @@ rpcsvc_callback_submit (rpcsvc_t *rpc, rpc_transport_t *trans,
         int                    ret         = -1;
         int                    proglen     = 0;
         uint32_t               xid         = 0;
+        gf_boolean_t           new_iobref  = _gf_false;
 
         if (!rpc) {
                 goto out;
@@ -1078,11 +1093,22 @@ rpcsvc_callback_submit (rpcsvc_t *rpc, rpc_transport_t *trans,
                         "cannot build rpc-record");
                 goto out;
         }
+        if (!iobref) {
+                iobref = iobref_new ();
+                if (!iobref) {
+                        gf_log ("rpcsvc", GF_LOG_WARNING, "Failed to create iobref");
+                        goto out;
+                }
+                new_iobref = 1;
+        }
+
+        iobref_add (iobref, request_iob);
 
         req.msg.rpchdr = &rpchdr;
         req.msg.rpchdrcount = 1;
         req.msg.proghdr = proghdr;
         req.msg.proghdrcount = proghdrcount;
+        req.msg.iobref = iobref;
 
         ret = rpc_transport_submit_request (trans, &req);
         if (ret == -1) {
@@ -1096,6 +1122,9 @@ rpcsvc_callback_submit (rpcsvc_t *rpc, rpc_transport_t *trans,
 out:
         iobuf_unref (request_iob);
 
+        if (new_iobref)
+               iobref_unref (iobref);
+
         return ret;
 }
 
diff --git a/rpc/rpc-lib/src/rpcsvc.h b/rpc/rpc-lib/src/rpcsvc.h
index 63a6dad8c2f..cf3e5906de1 100644
--- a/rpc/rpc-lib/src/rpcsvc.h
+++ b/rpc/rpc-lib/src/rpcsvc.h
@@ -581,7 +581,8 @@ int rpcsvc_request_submit (rpcsvc_t *rpc, rpc_transport_t *trans,
 
 int rpcsvc_callback_submit (rpcsvc_t *rpc, rpc_transport_t *trans,
                             rpcsvc_cbk_program_t *prog, int procnum,
-                            struct iovec *proghdr, int proghdrcount);
+                            struct iovec *proghdr, int proghdrcount,
+                            struct iobref *iobref);
 
 rpcsvc_actor_t *
 rpcsvc_program_actor (rpcsvc_request_t *req);